Continuous production of alcohols from biogenic syngas

(M.Sc. Anne Oppelt)

Climate change and the finite nature of fossil raw materials has led to an increasing interest in production processes based on renewable raw materials. One approach to the production of organic chemicals is the gasification of organic residues and the use of the synthesis gases obtained with acetogenic microorganisms.

Biogenic synthesis gases mainly consist of the two greenhouse gases carbon monoxide (CO) and carbon dioxide (CO2), as well as hydrogen (H2), which can be converted into organic acids and alcohols during gas fermentation by acetogenic microorganisms. Due to the low added value in gas fermentation for the production of alcohols, processes with high carbon conversions, high product concentrations, and high volumetric productivities (space-time yields), i.e. continuous processes, are required. However, since the growth rates in gas fermentation are low, the acetogenic microorganisms must be restrained in the continuously operated bioreactor (decoupling of the residence times).

The aim of this research project is to investigate the conversion of real biogenic synthesis gases with Clostridium autoethanogenum and Clostridium ragsdalei to alcohols such as ethanol and 2,3-butanediol in fully controlled, continuously gassed and continuously operated bioreactors with integrated cell retention in order to achieve high carbon conversions and space-time yields. For this purpose, real synthesis gas is provided by the Chair of Energy Systems at the Technical University of Munich.

The doctoral project is part of the project ‘GOLD - Bridging the gap between phytosanitation solutions on contaminated soil and clean biofuel production´ which is funded by the European Union's Horizon 2020 research and innovation program. It consists of an international consortium of partners from the EU, Canada and India.


  • Oppelt A, Rückel A, Rupp M, Weuster-Botz D (2024): Mixotrophic syngas conversion enables the production of meso-2,3-butanediol with Clostridium autoethanogenum. Fermentation 10: 102.
  • Rückel A, Oppelt A, Leuter P, Johne P, Fendt S, Weuster-Botz D (2022): Conversion of syngas from entrained flow gasification of biogenic residues with Clostridium carboxidivorans and Clostridium autoethanogenumFermentation 8: 465.